You’re including weekends in your calculation :) I believe OP is talking about contract/freelance work where you only get paid for the days you work.
For a fair comparison vs a full time job in the U.K. when I compared the two recently, I was using 226 working days per year (261 week days - 8 bank holidays - 27 paid holiday days). Of course if you don’t want to take so much holiday or want to and can work weekends then you’ll earn more!
650 x 226 is £144,460 for the record, still nothing to complain about!